The purpose of this research is to investigate and develop the potential usefulness of photochemotherapy as an approach to the management of malignant tumors, particularly brain tumors. We plan to define the conditions necessary to develop selective destruction by exposure to light of tumor cells sensitized by hematoporphyrin in vitro and in vivo, to develop suitable light sources for exciting intracellular hematoporphyrin, to prepare purified hematoporphyrin for in vitro and in vivo studies, to develop simple and easy methods to predict the effectiveness of photodynamic agents by in vitro assays, and to compare the metabolic properties of capillaries from brain tumors with capillaries from normal brain. BIBLIOGRPHIC REFERENCES: Openshaw, H. and Diamond, I. Extraction of D-beta hydroxybutyrate by brain in diabetic rats. Arch. Neurol. 32: 640-641 (Sept.) 1975. Goldstein, G.W., Wolinsky, J.S., Csejtey, J. and Diamond, I. Isolation of metabolically active capillaries from rat brain. J. Neurochem. 25:715-717, 1975.